Different human have different colors of chakra, and it does not depend on the character's race or power; instead, the color is determined by person personality.

Some particular humans have a shape or manifestation of their chakra whenever they release enough of it. The manifestations are one of the human inner strength/chakra.High level of chakra pressure can make an opponent feel as though they are being attacked though nothing is physically happening to them.In high enough quantities, chakra pressure can be lethal to others. When two spiritual beings collide, the side with weaker chakra pressure will get hurt.

Chakra at its most basic level can instill fear in others when it is very high (in comparison to the one feeling it). Willpower is the simplest way to fight this effect.

High level of chakra power can cause those of lower power to be stunned by simply being in the presence of a high level spiritual being.When a chakra being of high reiatsu chooses to they can paralyze an opponent just by focusing pressure through their stare or presence.

Zanjutsu

A Zanpakutō (斬魄刀; literally, soul-cutter sword) is the main weapon of the Shinobi, the Arrancar and the Visored. The Shinobi art of wielding a Zanpakutō is called Zanjutsu (斬術; literally, swordsmanship).

The Zanpakutō of low-ranking Shinobi are called Asauchi and don't have names, but the Zanpakutō of Shinobi of rank have names. In its sealed state, a Zanpakutō has the form of a Japanese sword.[1] Such weapons are unique swords generated from their owners souls. Its shape differs depending on its owner.[2]

Zanpakutō are the trademark weapons of the Shinobi. Capable of cutting spiritual bodies, they are amongst the few weapons which can be used to combat Hollows. Each Shinobi carries a Zanpakutō, and each Zanpakutō is unique: as the swords are both reflections of a Shinobi's soul and power, and sentient beings unto themselves. The Zanpakutō's name is also the name of the living spirit that empowers the sword and lends its strength to the Shinobi who wields it. These beings can vary greatly in appearance and have their own distinct personalities which match their owner's.

A Zanpakutō's shape and abilities are based on their Shinobi's soul. Once a Shinobi learns his/her sword's name, they are able to communicate with one another and grow stronger together. Zanpakutō are born with their Shinobi and they die along with their Shinobi. Shinobi use them in battle as a reflection of their heart. When released, they can display a vibrant power. They are one with the Shinobi, and they share a Shinobi's conviction.[3]

Inside each Zanpakutō is an incarnation that manifests itself upon the Zanpakutō's transformation. The first step is to acquaint oneself with this incarnation.[4]